Page:Popular Science Monthly Volume 37.djvu/765

 to the Georgia sea-islands of ante-bellum fame, may be mentioned as familiar examples the barriers which in Virginia and North Carolina separate Albemarle and Pamlico Sounds from the ocean; in Florida, Amelia Island on which is built the city of Fernandina; Anastasia Island, in front of St. Augustine; and the beaches which separate Halifax and Indian Rivers from the Atlantic. The last-named rivers are the lagoons which separate the barriers from the mainland shore. Lake Worth is one of these lagoons, of which the inlet has been closed.

To what extent the Florida Keys may be included in the category of barrier beaches must be decided by future investigation. Key West is evidently a wave-built sand-bar composed of fragments of coral, molluscan shells, and foraminifera, and it seems likely that Cayo Largo and others of that type may be of similar origin. The coquina deposits of the vicinity of St. Augustine are also wave-formed.

The hypothesis of Prof. Louis Agassiz, that the Florida Keys are all of organic origin—i. e., that they were formed by the growth of coral reefs—may be true so far as the determination of their location and direction. A submerged reef of coral may have formed a nucleus on which the waves and currents deposited a load of calcareous sand, but the superficial portion is evidently similar in origin to that of the beaches farther north.

Barrier beaches are found on all the sea-coasts of the world where opportunity for their growth has been afforded, and those of New Jersey may be regarded as types of these formations in all their essential features.

 

S an officer of the medical department of the United States Army, the writer was assigned to the military department of Arizona in 1884, and took station at Fort Verde, in the central part of that territory, in March. Strange were the sensations that we experienced on the morning succeeding our arrival, as we looked for the first time upon the broad valley of the Rio Verde, hemmed in by rugged mountains on the west, and terraced limestone cliffs with intervening mesas on the east. To the northward Beaver Creek poured its turbid flood into the Verde, whose banks were filled to overflowing by the waters sent down by the melting snow upon the distant Mogollon Mountains. Eighty miles to the north, beyond the ruddy cliffs of the "Red Rock Country," San Francisco Peak, the highest point and most prominent landmark in the territory, gleamed in snowy 